Portable air conditioner

ABSTRACT

A portable air conditioner comprises a tank for storing a liquid therein, a plurality of tubes, and at least one fin disposed between adjacent tubes. The tubes are spaced from one another defining an air passageway therebetween having an air inlet and a dry air outlet. Each tube has a first end extending into the tank in fluid communication with the liquid and a second end extending opposite the tank defining a wet air outlet and a wicking material disposed therein and in fluid communication with the liquid. A sheet valve sealingly engages the dry air outlet and the wet air outlet and is moveable for adjusting an amount of air flow exiting from the dry air outlet and the wet air outlet. At least one aperture is defined within each of the tubes between the ends to divert air flowing through the air passageway into the tubes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a portable air conditioner, and morespecifically to a personal, portable air conditioner that does notrequire a compressor and that is able to provide dry air as well as wetair separately.

2. Description of the Related Art

Various types of air conditioners are well known. The most common typeof air conditioner is commonly referred to as a vapor compression airconditioner. The vapor compression air conditioner comprises acondenser, an evaporator, a compressor, and an expansion deviceoperating in a closed loop. A working fluid circulates within the closedloop. The working fluid enters the compressor as vapor under lowpressure and the compressor compresses the vapor to form a super heatedvapor that passes through the condenser. A blowing device moves outsideair across the condenser and the condenser gives off heat to the outsideair thereby warming it. The working fluid exits the condenser as a highpressure liquid and passes through the expansion device to lower thepressure. The low pressure liquid then enters the evaporator and asecond blowing device moves outside air across the evaporator resultingin the working fluid evaporating. The evaporation of the working fluiddraws heat from outside air that is cooled. One drawback of the vaporcompression air conditioners is the requirement of the two heatexchangers, two blowing devices, the working fluid, and the compressor.The vapor compression air conditioners tend to be large and bulky andare generally not portable because of the numerous components. The useof a compressor significantly impacts the weight and bulkiness of theair conditioner resulting in a less portable air conditioner. Moreover,the working fluids are generally not environmentally safe and may bepossibly harmful or toxic if exposed to the user.

Another common type of air conditioner is referred to as a directevaporative air conditioner. The direct evaporative air conditionercomprises a liquid source, such as a pool of water, and hot air passesdirectly over the surface of the liquid. Energy from the air istransferred for evaporating the liquid, which results in a drop of thetemperature of the air. As the temperature drops, the absolute humidityof the air increases. However, one draw back to direct evaporative airconditioners, commonly called “swamp coolers”, is that the conditionedair carries odors that are present in the liquid source. One example ofa direct evaporative air conditioner utilizes a frozen liquid as asource to cool the air. These types of air conditioners are able toprovide cooling and possibly filtration of the air. However, these airconditioners do not provide the capability dividing an ambient airstream into a desired dry air stream and a humidified air stream.Further, these air conditioners do not include adjustment mechanism toregulate the amount of cooling that is occurring with the air tocoincide with the comfort of the user.

Still another common type of air conditioner is an indirect evaporativeair conditioner. Indirect evaporative air conditioners generally have awet channel with a first air moving device and a dry channel with asecond air moving device. The first air moving device directs a streamof air through the wet channel and the second air moving device directsair through the dry channel. The air flowing through the wet channelcarries water vapor that is evaporated from the air contacting the drychannel. These types of indirect evaporative air conditioners areinefficient because of the two air moving devices. Moreover, the twodevices result in a more heavy and bulky, i.e., less portable, airconditioner.

Accordingly, it would be advantageous to provide a portable airconditioner that overcomes the inadequacies that characterize therelated art air conditioners.

SUMMARY OF THE INVENTION AND ADVANTAGES

The subject invention provides a portable air conditioner comprising atank for storing a liquid therein, a plurality of tubes, and at leastone fin disposed between adjacent tubes. The tubes are spaced from oneanother defining an air passageway therebetween having an air inlet anda dry air outlet for dispensing dry air therefrom. Each of the tubeshave a first end extending into the tank in fluid communication with theliquid and a second end extending opposite the tank defining a wet airoutlet for dispensing wet air therefrom and a wicking material disposedtherein. The air conditioner also includes a sheet valve sealinglyengaging the dry air outlet and the wet air outlet. The sheet valve ismoveable for adjusting an amount of air flow exiting from the dry airoutlet and the wet air outlet. The subject invention also includes atleast one aperture defined within each of the tubes between the ends fordiverting air flowing through the air passageway into the tubes andexiting through the wet air outlet.

The subject invention overcomes the inadequacies that characterize therelated art air conditioners. Specifically, the subject inventionprovides an air conditioner that cools air without requiring acompressor, which results in a light weight portable unit. The subjectinvention can also separately cool the air and provide humidification tothe air separately. The air conditioner according to the subjectinvention may also adjust the amount of cooling and/or humidification tomore closely coincide with the comfort of the user.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a front perspective view of a portable air conditioneraccording to the subject invention;

FIG. 2 is a rear perspective view of the portable air conditioner shownin FIG. 1;

FIG. 3 is a front perspective view of the portable air conditioner ofFIG. 1 having a fan module removed therefrom;

FIG. 4 is an exploded front perspective view of the portable airconditioner shown in FIG. 1;

FIG. 5 is a schematic circuit diagram of the portable air conditioner;

FIG. 6 is a representation of wet and dry air streams flowing throughthe portable air conditioner on a psychrometric chart.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a portable air conditioner is showngenerally at 10 in FIG. 1. It is to be appreciated that the portable airconditioner 10 may be used by a single user, i.e., personal. Further,the portable air conditioner 10 does not require a compressor therebyreducing the weight of the air conditioner 10 and increasing theportability. The portable air conditioner 10 is particularly useful inbuildings as well as in outdoor environments. For example, the airconditioner 10 may be used during war times or in the medical field. Thesubject invention is capable of providing sufficiently conditioned airin various climates, such as hot and dry climates, hot and humidclimates, or cool and dry climates. The portable air conditioner 10 ofthe subject invention may also be used in series with a heater, such asan electric heater to further warm air exiting therefrom.

The portable air conditioner 10 generally comprises a tank 12 forstoring a liquid therein, a plurality of tubes 14, and at least one fin16 disposed between adjacent tubes 14. The tank 12 may be formed ofvarious materials, such as plastic or metal materials. However, in orderto reduce the weight of the air conditioner 10, it is preferable to formthe tank 12 from plastic materials. Moreover, the tank 12 may be formedfrom a transparent material in order to view the level of the liquidwithin the tank 12. The tank 12 may also be omitted or remain unfilledto operate the air conditioner 10 as a ventilator.

The tank 12 is shown in the Figures as a generally rectangularly shapedtank 12 with four sides having slots 18 (shown best in FIG. 4) in a topfor receiving the tubes 14. The connection between the tubes 14 and thetank 12 may be sealed by any well known sealing methods, if desired, toprevent the liquid from escaping. The tank 12 also includes a liquidinlet 20 for allowing additional liquid to be supplied to the tank 12.The liquid inlet 20 may be able to be connected to a water source, suchas a faucet or a hose. The tank 12 optionally may include a sensor (notshown) to indicate the level of the liquid therein or have a valve (notshown) connected to the water supply for actuating a filling mechanismto re-fill the tank 12. The liquid within the tank 12 is preferablywater; however, other liquids may be utilized without deviating from thesubject invention.

Referring back to FIG. 1, the air conditioner 10 has the plurality oftubes 14 spaced from one another. It is to be appreciated by those ofordinary skill in the art that the air conditioner 10 may bemanufactured with as few as two tubes 14 or with as many as fifty tubes14. The number of tubes 14 is not intended to limit the subjectinvention. The tubes 14 are spaced from one another and define an airpassageway 22 therebetween. The air passageway 22 has an air inlet 24for ambient air 100 to enter and a dry air outlet 26 for dispensing dryair 110 therefrom. In other words, the air passageway 22 acts as a drychannel. Ambient air enters the air inlet 24 as illustrated by arrow 100and dry air exits the dry air outlet 26 as illustrated by arrow 110,both in FIG. 1.

The subject invention may also include a fan module 28 adjacent the airinlet 24 for directing a flow of ambient air 100 though the airpassageway 22 as shown in FIG. 1. The fan module 28 increases the amountof ambient flowing into the air passageway 22. The fan module 28 may beremovable from the air conditioner 10 or permanently mounted thereon.The fan module 28 may be any well known type of fan, such as an axialfan or centrifugal fan. However, it is preferred that an axial fan isused to concentrate the flow of ambient air 100 through the airpassageway 22.

The portability of the air conditioner 10 is increased by providing apower supply to operate the fan module 28. It is desirable that thepower supply be small and light weight and be able to sufficiently powerthe fan module 28. For example, the power supply may be a battery 30.Alternatively, the power supply may comprise a solar panel 32 with aplurality of solar cells 34 as shown in the Figures. This isparticularly advantageous if the portable air conditioner 10 is used inoutdoor environments. The use of the solar panels 32 result in aself-adjusting system for comfort cooling. In other words, if the sun ispresent, more cooling will be needed and the solar panels 32 willprovide more voltage for operating the fan module 28.

The subject invention may also utilize a combination of power supplies.A schematic circuit diagram of the air conditioner 10 is shown in FIG.5. The circuit diagram includes a dual power supply, the solar panel 32,and an auxiliary supply, such as the battery 30. The solar panel 32supplies power to the fan module 28 through a first diode 40 and the airconditioner 10 has two ground points 38 that complete the circuit. Thebattery 30 feeds power to the fan module 28 through a second diode 36.Thus, the fan module 28 may be powered by whichever power supply has thehigher voltage. The first diode 40 prevents back feeding power from thebattery 30 into the solar panel 32 and the second diode 36 prevents backfeeding power from the solar panel 32 into the battery 30. As anotherpower supply, a hand generator (not shown) may also be used in place ofeither the solar panel 32 or the battery 30.

Referring back to FIGS. 1 through 4, each of the tubes 14 have a firstend 42 extending into the tank 12 in fluid communication with the liquidand a second end 44 extending opposite the tank 12. The first end 42 issufficiently open to allow the liquid to enter inside of the tube 14.The second end 44 extends opposite the tank 12 defining a wet air outlet46 for dispensing wet air 120 therefrom, which is illustrated by arrow120 in FIG. 1. In other words, the inside of the tubes 14 defines a wetchannel. The tubes 14 may be formed of various materials that are lightweight, such as plastic or metal materials. Further, the tubes 14 arepreferably generally flat, oval shaped tubes 14, however, various shapesof tubes 14 may be used with the subject invention without being limitedto the embodiments shown.

At least one fin 16 is disposed between adjacent tubes 14. Preferably,an array of fins 16 are disposed between adjacent pairs of tubes 14 asunderstood by those of ordinary skill in the art. The fins 16 arepreferably formed of a material having good heat transfer properties.One suitable material would include a metal material. The fin 16 may bea plain fin, a corrugated fin, or a louvered fin. Preferably, the fin 16is a louvered fin for allowing air to pass vertically through the airpassageway 22 and increase heat transfer therebetween.

The tubes 14 also include at least one aperture 48 defined within eachof the tubes 14. The apertures 48 are located between the ends 42, 44for diverting air flowing through the air passageway 22 into the tubes14 and exiting through the wet air outlet 46. As shown in the Figures,the apertures 48 are located between the first and second ends 42, 44and are closer to the first end 42, while remaining above the tank 12.In other words, as ambient air 100 flows through the air passageway 22,a fraction of the air is diverted through the aperture 48 and into thetube 14. The number and size of apertures 48 are determined to ensure adesired amount of air is flowing through the dry air outlet 26 and thewet air outlet 46.

A wicking material 50 is disposed within at least one of the tubes 14and is in fluid communication with the liquid. Preferably, the wickingmaterial 50 is a fibrous material, such as fabric or cloth. The wickingmaterial 50 wicks the liquid from the tank 12 via capillary action upthe tube 14. Preferably, the wicking material 50 extends along asubstantial portion of the tube 14, such as more than fifty percent ofthe length of the tube 14. However, different amounts of wickingmaterial 50 may be used to achieve various results. The ambient air 100entering the air passageway 22 transmits energy to the fin 16 andthrough the tube 14 to evaporate the liquid in the wicking material 50.As the liquid evaporates, the humidity of air exiting the wet air outlet46 increases in humidity. Further, the air passing through the airpassageway 22 and exiting the dry air outlet 26 is cooled. As will bedescribed further below, the dry air 110 exiting the dry air outlet 26may have the same humidity as the ambient air 100 entering the airpassageway 22.

A sheet valve 52 sealingly engages the dry air outlet 26 and the wet airoutlet 46. The sheet valve 52 is moveable relative to the air outlets26, 46 for adjusting an amount of air flow exiting from the dry airoutlet 26 and the wet air outlet 46. The air conditioner 10 according tothe subject invention is operable in four modes: 1) cooling mode, 2)ventilation mode, 3) heating mode, and 4) humidification mode. In thecooling mode, the sheet valve 52 is in a halfway position, as shown inthe Figures, such that half of the dry air outlet 26 is blocked by thesheet valve 52. Since the ambient air 100 is not able to pass straightthrough the air passageway 22, the ambient air 100 remains in contactwith the fins 16, thereby transferring additional energy to evaporatethe liquid on the wicking material 50. Also, the ambient air 100 isforced downward and into the apertures 48 thereby increasing the amountof wet air 120 exiting the wet air outlet 46.

In the ventilation mode, the sheet valve 52 would be positioned entirelyclosing the wet air outlet 46, thereby passing all the ambient air 100straight through the air passageway 22. The dry air 110 will likely havethe same humidity as the ambient air 100 with a lower temperature whenexiting the dry air outlet 26. In the heating mode, an additional heater(not shown) may be positioned adjacent the dry air outlet 26 to heat thedry air 110. In the humidification mode, the sheet valve 52 ispositioned entirely closing the dry air outlet 26, forcing all theambient air 100 through the apertures 48 and into the tubes 14 resultingin an increased flow of wet air 120 exiting the wet air outlet 46.

The subject invention also includes an adjustment mechanism 54operatively connected to the sheet valve 52 for moving the sheet valve52. The adjustment mechanism 54 can be operated manually orautomatically. Adjusting the sheet valve 52 serves as a thermostat toregulate a desired temperature by adjusting amounts of air flowingtherefrom. In the embodiment shown, the adjustment mechanism 54 is aknob that allows a user to rotate the knob and move the sheet valve 52accordingly depending upon the preference of the user. It is to beappreciated by those of ordinary skill in the art that other adjustmentmechanisms 54 may be used with the subject invention.

In order to ensure the flow of the ambient air 100 through the airconditioner 10, at least one first flow plate 56 is disposed between thetubes 14 and adjacent the second ends 44 for sealing the air passageway22. In other words, the first flow plate 56 seals the top of the airpassageway 22 to reduce ambient air 100 from escaping from the top ofthe air condition. Referring to FIG. 4, two first flow plates 56 areshown sealing between the three tubes 14. Additionally, at least onesecond flow plate 58 is disposed adjacent the dry air outlet 26 forsealing the tubes 14. Said another way, the second flow plates 58prevent ambient air 100 from escaping from the air passageway 22. InFIG. 4, three second flow plates 58 are illustrated positioned at therear of each of the tubes 14. Standard sealing devices or seals may beused in place of either or both of the first and second flow plates 56,58 so long as the ambient air 100 sufficiently contacts the fins 16 totransfer energy therebetween.

Another feature of the subject invention is that a cartridge 60 may bedisposed adjacent at least one of the dry air outlet 26 and the wet airoutlet 46. The cartridge 60 may be a filter to remove particles fromeither wet air 120 or the dry air 110 or may be an aroma filter to addan aroma to the same. In one embodiment, the cartridge 60 is disposed ina cartridge slot 62 that may be defined between the sheet valve 52 andthe humid or dry air outlets 26. In FIG. 2, the cartridges 60 are showndisposed within the dry air outlet 26. An additional filter (not shown)may be mounted between the air inlet 24 and the fan module 28, ifdesired, to remove particles from the ambient air 100, such as sand,dirt, or the like, prior to entering the air conditioner 10.

Referring to FIG. 6, the state of the ambient air 100 is shown as itenters the portable air conditioner 10 and flows through the passageways22 exiting as the dry air stream 110. It also shows the state of the wetair stream 120 fractioned off from the incoming air stream at theapertures 48 and directed through the wet air passageways 46.

The horizontal axis of the psychrometric chart represents the dry bulbtemperature, T_(db), of air while the vertical axis represents theabsolute humidity, ω, of air, which is the mass of water vapor in unitmass of dry air 110. The other measure of the moisture content of air,namely relative humidity, φ, is also indicated on the psychrometricchart as a parameter on the two curves labeled φ=1 and φ=φ_(i). Thecurve φ=1 represents the fully saturated air with 100% relative humidityand the curve φ=φ_(i) represents the partially saturated incomingambient air 100 with relative humidity φ_(i)<1. Relative humidity, φ, isthe ratio of the mass of water vapor in a given volume of air to thatnecessary to saturate it at the same temperature.

The state of ambient air stream 100 entering the portable airconditioner 10 with dry bulb temperature, T_(i), relative humidity,φ_(i), and absolute humidity φ_(i) is represented by point on thepsychrometric chart. The fraction of the ambient air stream 100 thatmoves along the line 1→3 with its absolute humidity, ω_(i), remainingfixed but relative humidity increasing from φ_(i) to 1 is the dry air110. At the same time the dry bulb temperature, T_(i), of the dry airstream 110 decreases from T_(i) to T_(dpi), which is the dew pointtemperature of air corresponding to the inlet conditions. It is thelowest dry bulb temperature that the dry air stream 110 can attain withfixed absolute humidity, ω_(i). T_(dpi) is expressible as$\begin{matrix}{T_{dpi} = {T_{wt}\left\{ {1 - {\frac{1}{\alpha}{\ln\left\lbrack \frac{\omega_{i}{P_{amb}/P_{wt}}}{\omega_{i} + {M_{w}/M_{a}}} \right\rbrack}}} \right\}^{{- 3}/4}}} & (1)\end{matrix}$

where

T_(wt) is the triple point temperature of water=491.6880° R.

P_(wt) is the triple point pressure of water=0.088663 psi.

P_(amb) is the atmospheric pressure=14.696 psi.

M_(a) is the molecular weight of air=28.9645 lb_(m)/lbmole.

M_(w) is the molecular weight of water=18.0152 lb_(m)/lbmole.

ω_(i) is the absolute humidity of the incoming air, lb_(m) H₂O/lb_(m)dry air.

α is a dimensionless constant=15.0197.

In FIG. 6, the temperature increases from left to right and the absolutehumidity increases from bottom to top. It may be noted that dew pointtemperature is the lowest temperature that air can attain without anymoisture addition. As the air temperature tends to the dew point, itscapacity to hold water vapor diminishes and upon reaching the dew pointit no longer can hold the water vapor, which then condenses out of theair as liquid water.

In view of the inherent inefficiencies in the system, the actual drybulb temperature, T_(do), attained by the dry air stream 110 is somewhathigher than T_(dpi) as indicated at point on the psychrometric chart.

In the maximum comfort cooling mode, the wet air stream 120 exitingthrough the wet passageways 46 takes the path 1→6 indicated on thepsychrometric chart. In this mode of operation, the dry bulb temperatureof the wet air stream 120 remains fixed at T_(i), but its absolutehumidity increases from ω_(i) to ω_(∞) with relative humidity increasingfrom φ_(i) to 1. The absolute humidity, ω_(∞), of the wet air stream 120exiting the wet passageways 46 is expressible as $\begin{matrix}{\omega_{\infty} = \frac{M_{w}/M_{a}}{{\left( {P_{amb}/P_{wt}} \right)\exp\left\{ {\alpha\left\lbrack {\left( {T_{wt}/T_{i}} \right)^{4/3} - 1} \right\rbrack} \right\}} - 1}} & (2)\end{matrix}$

Corresponding to the ω_(∞), the dry bulb temperature T_(do) attained bythe dry air stream 110 flowing through the dry passageways 22 isexpressible as $\begin{matrix}{T_{do} = {T_{i}\frac{\lambda\quad{h_{fg}\left( {\omega_{\infty} - \omega_{i}} \right)}}{c_{pa}}}} & (3)\end{matrix}$

where in addition to the previously defined symbols

λ is the mass fraction of the ambient air stream 100 diverted into thewet passageways 46, i.e., it is the ratio of the mass flow rate of thewet air stream 120 to the mass flow rate of the ambient air stream 100.

c_(pa) is the isobaric specific heat of air, Btu/lb_(m)° R.

h_(fg) is the latent heat of evaporation of water given as$\begin{matrix}{h_{fg} = {\beta\left( {1 - \frac{T_{i}}{T_{c}}} \right)}^{3/8}} & (4)\end{matrix}$

where in addition to the previously defined symbols

β is a constant=1300.26 Btu/lb_(m).

T_(i) is the dry bulb temperature of the incoming ambient air, ° R.

T_(c) is the critical temperature of water=1165.11° R.

The absolute humidity ω_(i) of the incoming ambient air 100 isexpressible as $\begin{matrix}{\omega_{i} = \frac{\left( {M_{w}/M_{a}} \right)\phi_{i}}{{\left( {P_{amb}/P_{wt}} \right)\exp\left\{ {\alpha\left\lbrack {\left( {T_{wt}/T_{i}} \right)^{4/3} - 1} \right\rbrack} \right\}} - \phi_{i}}} & (5)\end{matrix}$

where in addition to the previously defined symbols φ_(i) is therelative humidity of the incoming ambient air 100.

The rate of evaporation of water in the maximum comfort cooling mode isexpressible as{dot over (m)} _(w) =λ{dot over (m)} _(a)(ω_(∞)−ω_(i))  (6)

where in addition to the previously defined symbols

{dot over (m)}_(w) is the rate of evaporation of water in the portableair conditioner 10, lb_(m)/min.

{dot over (m)}_(a) is the mass flow rate of ambient air 100 flowing intothe portable air conditioner 10, lb_(m)/min.

The mass fraction, λ, of air required to attain the lowest comfortcooling temperature, T_(dpi), is expressible asλ=c _(pa)(T _(i) −T _(dpi))/(ω_(∞)−ω_(i))h _(fg)  (7)

where all the symbols have been previously defined.

In the humidification mode, the incoming ambient air stream 100 isdirected through the wet passageways 46 by closing the dry passagewaysby means of the sheet valve 52. In this case, the path taken by the wetair stream 120 is indicated by the line 1→5 on the psychrometric chart.In the humidification mode, the lowest dry bulb temperature attained bythe wet air stream 120 is the wet bulb temperature T_(dpo) correspondingto the absolute humidity ω_(w) indicated on the psychrometric chart. Thewet bulb temperature is the temperature attained by air as it becomessaturated with water vapor evaporating into the air from an externalsource, such as saturated wicking material 50 lining the passageways 46,resulting in an increase in the absolute humidity of the air. The wetbulb temperature must be distinguished from the dew point temperature,which is the temperature attained by air as it becomes saturated withwater vapor within the air itself, i.e., without water addition from anexternal source. Thus unlike the wet bulb temperature the dew pointtemperature is attained with no change in the absolute humidity of theair.

T_(dpo) and ω_(w) can be determined using the following two independentrelations expressing ω_(w) explicitly as a function of T_(dpo):ω_(w) =M _(w) /M _(a)/(P _(amb) /P _(wt))exp{α[(T _(wt) /T_(dpo))^(4/3)−1]}−1  (8)ω_(w)=ω_(i)+(c _(pa)+ω_(i) c _(pw))(T _(i) −T _(dpo))/h _(ao)+32c_(f)−(c _(f) −c _(pw))T _(dpo)  (9)

where in addition to the previously defined symbols

c_(pa) is the isobaric specific heat of air=0.24 Btu/lb_(m)° R.

c_(pw) is the isobaric specific heat of water vapor=0.444 Btu/lb_(m)° R.

c_(f) is the isobaric specific heat of liquid water=1 Btu/lb_(m)° R.

h_(ao) is the reference enthalpy of air=1061 Btu/lb_(m).

Unfortunately Eqs. (8) and (9) cannot be solved in closed form todetermine T_(dpo) and ω_(w) explicitly. They need to be solvediteratively to determine T_(dpo) and ω_(w). The iterative procedure canproceed as follows. Assume an initial lower bound value ofT_(dpo)=T_(dpi) where T_(dpi) is given in Eq. (1). With this value ofT_(dpo) determine ω_(w) using Eqs. (8) and (9). If the two values ofω_(w) do not match, assume a higher value of T_(dpo) and calculate a newset of ω_(w) values using Eqs. (8) and (9). Continue the iterativeprocedure till the two values of ω_(w) match. The corresponding assumedvalue of T_(dpo) will then represent the desired value of T_(dpo).

In the humidification mode, the entire ambient air stream 100 isdirected through the passageways 46. The humidified air emerges from airconditioner 10 as cold and wet air stream 120 with no air emerging fromthe dry passageways 22. In other words, the mass flow rate of the wetair stream 120 is equal to the mass flow rate of the ambient air stream100. In this case, the rate of consumption of liquid water to producethe absolute humidity and the wet bulb temperature given by Eqs. (8) and(9) is given by{dot over (m)} _(w) ={dot over (m)} _(a)(ω_(w)−ω_(i))  (10)

Having presented the useful analytical relations, numerical examples arepresented next to illustrate some useful quantitative results generatedtherefrom for the portable air conditioner 10.

EXAMPLE

Calculate the lowest temperature of the conditioned dry air stream 110produced by the portable air conditioner 10 if the dry bulb temperatureof the ambient air 100 is 100° F. and its relative humidity is 40%.

The lowest temperature attained by the dry air stream 110 in theportable air conditioner 10 is the dew point temperature T_(dpi) givenby Eq. (1) corresponding to the initial absolute humidity ω_(i), whichneeds to be determined first corresponding to the given ambient air 100temperature T_(i)=100° F.=559.67° R and the relative humidityφ_(i)=0.40. Introducing these values into Eq. (5) together withM_(a)=28.9645 lb_(m)/lbmole, M_(w)=18.0152 lb_(m)/lbmole, P_(amb)=14.696psi, P_(wt)=0.088663 psi and T_(wt)=491.6880° R, we obtainω_(i)=0.016685 lb_(m) H₂O/lb_(m) dry air 110. Introducing this value ofω_(i) together with α=15.0197 into Eq. (1), we obtain the value of thelowest temperature attained by the air as T_(dpi)=531.1° R=71.4° F.

Example 2

Determine the maximum absolute humidity of the wet air stream 120attained in the portable air conditioner 10 in the comfort cooling modewhen the ambient air 100 temperature is 100° F.=559.67° R.

The maximum absolute humidity ω_(∞) of the wet air stream 120 attainedin the portable air conditioner 10 is given by Eq. (2). IntroducingM_(a)=28.9645 lb_(m)/lbmole, M_(w)=18.01521 lb_(m)/lbmole,P_(amb)=14.696 psi, P_(wt)=0.088663 psi, T_(wt)=491.6880° R,T_(i)=559.67° R and α=15.0197, we obtain ω_(∞)=0.043461 lb_(m)H₂O/lb_(m) dry air 110.

Example 3

Determine the mass fraction of the ambient air stream 100 to be divertedto the wet passageways 46 to attain the lowest temperature of theconditioned dry air stream 110 in the portable air conditioner 10 giventhe dry bulb temperature of the incoming ambient air 100 as 100° F. andits relative humidity as 40%.

The mass fraction λ of the ambient air stream 100 to be diverted to thewet passageways 46 to attain the lowest temperature of the conditioneddry air stream 110 in the portable air conditioner 10 is given by Eq.(7) where T_(dpi) is determined from Eq. (1), ω_(∞) is determined fromEq. (2), ω_(i) is determined from Eq. (5) and h_(fg) is determined fromEq. (4).

The lowest attainable temperature by the conditioned dry air stream 110corresponding to the prescribed ambient air temperature and relativehumidity is calculated to be T_(dpi)=531.1° R=71.4° F. in Example 1. Themaximum attainable absolute humidity of the wet air stream 120 emergingfrom the wet passageways 46 is ω_(∞)=0.043461 lb_(m) H₂O/lb_(m) dry air110 as calculated in Example 2. Also the absolute humidity of theincoming ambient air 100 ω_(i)=0.016685 lb_(m) H₂O/lb_(m) dry air 110 ascalculated in Example 1. The latent heat of evaporation of water h_(fg)needs to be calculated using Eq. (4). Introducing β=1300.26 Btu/lb_(m)°R, T_(i)=559.67° R, T_(c)=1165.11° R into Eq. (4), we obtainh_(fg)=1017.23 Btu/lb_(m).

Finally, introducing c_(pa)=0.24 Btu/lb_(m)° R, T_(i)=559.67° R,T_(dpi)=531.1° R, ω_(∞)=0.043461 lb_(m) H₂O/lb_(m) dry air 110 ° R,ω_(i)=0.0166850/lb_(m) H₂O/lb_(m) dry air 110 and h_(fg)=1017.23Btu/lb_(m), we obtain from Eq. (7), λ=0.2522. This means in order toattain the lowest temperature of the conditioned dry air stream 110 inthe portable air conditioner 10, 25.22% of the ambient air stream 100must be diverted to the wet passageways 46.

Example 4

It is required to determine the rate of consumption of liquid water inthe air conditioner 10 under conditions of attainment of the lowestconditioned air temperature given the dry bulb temperature of theincoming ambient air 100 as 100° F., its relative humidity as 40% andmass flow rate through the air conditioner 10 as 20 lb_(m)/min.

The rate of consumption of liquid water {dot over (m)}_(w) in theportable air conditioner 10 in the comfort cooling mode under conditionsof attainment of the lowest conditioned air temperature is given by Eq.(6). Under these conditions, the mass fraction λ of the ambient air 100diverted to the wet passageways 46 is calculated to be 0.2522 in Example3. The absolute humidity to) of the wet air 120 exiting the wetpassageways 46 is calculated to be ω_(∞)=0.043461 lb_(m) H₂O/lb_(m) dryair 110 in Example 2. The absolute humidity ω_(i) of the ambient air 100is calculated to be ω_(i)=0.016685 lb_(m) H₂O/lb_(m) dry air 110.Introducing these values into Eq. (6) together with the prescribed massflow rate of ambient air 100 {dot over (m)}_(a)=20 lb_(m)/min, we obtainthe rate of consumption of liquid water as {dot over (m)}_(w)=0.1351lb_(m)/min.

Example 5

It is required to determine the absolute humidity and the lowesttemperature of the moist air in humidification mode when the ambient air100 temperature is 100° F. with relative humidity 0.40 and absolutehumidity 0.016685 lb_(m) H₂O/lb_(m) dry air 110.

The absolute humidity ω_(w) and the lowest temperature of the moist airT_(dpo) in humidification mode can be determined by an iterative processwith the aid of Eqs. (8) and (9). As an initiatory step, we assumeT_(dpo)=T_(dpi)=531.1° R, which was calculated in Example 1. With thisassumed value of T_(dpo), we obtain ω_(w)=0.016685 lb_(m) H₂O/lb_(m) dryair 110 from Eq. (8) and ω_(w)=0.025556 lb_(m) H₂O/lb_(m) dry air 110from Eq. (9). Since these two values of ω_(w) do not match, weprogressively assume lower and lower values of T_(dpa) and calculate thecorresponding values of ω_(w). This iterative procedure is continuedtill the two values of ω_(w) converge. After a few iterations, we findthat at T_(dpo)=538.6° R=78.9° F., the two values of ω_(w) converge at0.021613 lb_(m) H₂O/lb_(m) dry air 110. Thus the lowest temperature ofthe wet air 120 T_(dpo)=78.9° F. and the corresponding absolute humidityof the wet air 120 exiting the air conditioner 10 in humidification modeis ω_(w)=0.021613 lb_(m) H₂O/lb_(m) dry air 110.

Example 6

It is required to determine the rate of consumption of liquid water inhumidification mode given the dry bulb temperature of the incomingambient air 100 as 100° F., its relative humidity as 40% and mass flowrate through the air conditioner 10 as 20 lb_(m)/min.

The rate of consumption of liquid water in humidification mode can becalculated with the use of Eq. (10). As calculated in Example 1, theabsolute humidity of the incoming ambient air 100 corresponding to itsdry bulb temperature of T_(i)=100° F. and relative humidity φ_(i)=40% isω_(w)=0.016685 lb_(m) H₂O/lb_(m) dry air 110. Also as calculated inExample, the absolute humidity of the humidified air ω_(w)=0.021613lb_(m) H₂O/lb_(m) dry air 110. Introducing these values of the absolutehumidity together with the prescribed mass flow rate {dot over(m)}_(a)=20 lb_(m)/min. into Eq. (10), we obtain the rate of consumptionof liquid water in humidification mode {dot over (m)}_(w)=0.0986lb_(m)/min.

In view of the above examples, the subject invention also provides amethod of providing conditioned air from the portable air conditioner10. The method may be used to control operation of the air conditioner10 to achieve a desired temperature of dry air 110 or humidity of thewet air 120. The method comprises determining an absolute humidity,ω_(i), for ambient air 100 having a initial temperature, T_(i), and arelative humidity, φ_(i), that enters the ambient air 100 inlet 24.Equation (5) is preferably used to determine ω_(i). It is to beappreciated that the above examples and equations were solved having theliquid as water and hence the constants reflects those for water. Ifdifferent liquids or different solutions o are used for the liquid, thenthe constants may also be different and the subject invention is notintended to be limited to using water as the liquid.

Next, an absolute humidity, ω_(∞), is determined for air exiting the wetair outlet 46 based upon T_(i); and a lowest obtainable temperature,T_(dpi), is determined for air exiting the dry air outlet 26 based uponω_(i). Equations (2) and (1) may be used to calculate GO and T_(dpi),respectively. Based upon T_(dpi), a predetermined portion of the wet airoutlet 46 and the dry air outlet 26 are blocked to divert the ambientair 100 stream into the apertures 48 to provide a desired temperature ofthe air exiting the dry air outlet 26. It is to be appreciated that theblocking of the outlets 26, 46 may be done automatically or manually.

The method also comprises determining the mass fraction, λ, of theambient air 100 stream to divert into the wet and dry passageways toachieve the desired temperature, as illustrated in Equation (7). As oneexample, the position of the sheet valve 52 may be adjusted to block thepredetermined portion of the wet air outlet 46 and the dry air outlet 26to achieve λ and the desired temperature. The air conditioner 10 mayinclude indicators (not shown) that allow for positioning of the sheetvalve 52 to achieve the desired outlet temperature based upon theambient air 100 conditions. Moreover, the air conditioner 10 may includea sensor (not shown), such as a thermocouple, that provides theconditions of the ambient air 100 to allow for adjusting of the airconditioner 10. Additionally, the method may adjust the flow rate of theambient air 100 into the ambient air inlet 24 to achieve the desiredtemperature.

While the invention has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A portable air conditioner comprising: a tank for storing a liquidtherein; a plurality of tubes spaced from one another defining an airpassageway therebetween having an air inlet and a dry air outlet fordispensing dry air therefrom; each of said tubes having a first endextending into said tank in fluid communication with the liquid and asecond end extending opposite said tank defining a wet air outlet fordispensing wet air therefrom; at least one fin disposed between adjacenttubes; a sheet valve sealingly engaging said dry air outlet and said wetair outlet and moveable for adjusting an amount of air flow exiting fromsaid dry air outlet and said wet air outlet; and at least one aperturedefined within each of said tubes between said ends for diverting airflowing through said air passageway into said tubes and exiting throughsaid wet air outlet.
 2. A portable air conditioner as set forth in claim1 further comprising a wicking material disposed within at least one ofsaid tubes and in fluid communication with the liquid such that airflowing into said air inlet transmits energy to said fin and throughsaid tube to evaporate the liquid in said wicking material and increasehumidity of air exiting said wet air outlet and cool air exiting saiddry air outlet.
 3. A portable air conditioner as set forth in claim 1further comprising a fan module adjacent said air inlet for directing aflow of ambient air though said air passageway.
 4. A portable airconditioner as set forth in claim 3 wherein said fan module is furtherdefined as an axial fan.
 5. A portable air conditioner as set forth inclaim 3 further comprising a power supply for operating said fan module.6. A portable air conditioner as set forth in claim 5 wherein said powersupply is further defined as a battery.
 7. A portable air conditioner asset forth in claim 5 wherein said power supply is further defined as asolar panel comprising a plurality of solar cells.
 8. A portable airconditioner as set forth in claim 1 further comprising an adjustmentmechanism operatively connected to said sheet valve for moving saidsheet valve.
 9. A portable air conditioner as set forth in claim 1further comprising a cartridge disposed adjacent at least one of saiddry air outlet and said wet air outlet.
 10. A portable air conditioneras set forth in claim 9 further comprising a cartridge slot forreceiving said cartridge.
 11. A portable air conditioner as set forth inclaim 9 wherein said cartridge is further defined as an aroma filter.12. A portable air conditioner as set forth in claim 1 wherein said finis further defined as a louvered fin for allowing air to pass verticallythrough said air passageway.
 13. A portable air conditioner as set forthin claim 1 further comprising at least one first flow plate disposedbetween said tubes and adjacent said second ends for sealing said airpassageway.
 14. A portable air conditioner as set forth in claim 13further comprising at least one second flow plate disposed adjacent saiddry air outlet for sealing said tubes.
 15. A portable air conditioner asset forth in claim 1 wherein said tank further comprises a liquid inletfor refilling said tank with the liquid.
 16. A portable air conditionercomprising: a tank for storing a liquid therein; a plurality of tubesspaced from one another defining an air passageway therebetween havingan air inlet and a dry air outlet for dispensing dry air therefrom eachof said tubes having a first end extending into said tank in fluidcommunication with the liquid and a second end extending opposite saidtank defining a wet air outlet for dispensing wet air therefrom; atleast one fin disposed between adjacent tubes; at least one aperturedefined within each of said tubes between said ends for diverting airflowing through said air passageway into said tubes and exiting throughsaid wet air outlet; and a wicking material disposed within at least oneof said tubes and in fluid communication with the liquid such that airflowing into said air inlet transmits energy to said fin and throughsaid tube to evaporate the liquid in said wicking material and increasehumidity of air exiting said wet air outlet and cool air exiting saiddry air outlet.
 17. A portable air conditioner as set forth in claim 16further comprising a sheet valve sealingly engaging said dry air outletand said wet air outlet and moveable for adjusting an amount of air flowexiting from said dry air outlet and said wet air outlet.
 18. A portableair conditioner as set forth in claim 17 further comprising anadjustment mechanism operatively connected to said sheet valve formoving said sheet valve.
 19. A portable air conditioner as set forth inclaim 17 further comprising a fan module adjacent said air inlet fordirecting a flow of air though said air passageway.
 20. A portable airconditioner as set forth in claim 16 wherein said wicking material isfurther defined as a fibrous material.
 21. A method of providingconditioned air from a portable air conditioner having a tank storing aliquid therein, a plurality of tubes defining an ambient air inlet and adry air passageway between adjacent tubes and defining at least oneaperture to allow air to enter inside of the tube defining a wet airpassageway, and a sheet valve sealingly engaging a dry air outlet and awet air outlet, said method comprising: determining an absolutehumidity, ω_(i), for ambient air having a initial temperature, T_(i),and a relative humidity, φ_(i), that enters the ambient air inlet;determining an absolute humidity, ω_(∞), for air exiting the wet airoutlet based upon T_(i); determining a lowest obtainable temperature,T_(dpi), for air exiting the dry air outlet based upon ω_(i); andblocking a predetermined portion of the wet air outlet and the dry airoutlet to divert the ambient air stream into the apertures to provide adesired temperature of the air exiting the dry air outlet based uponT_(dpi).
 22. A method as set forth in claim 21 further comprisingdetermining a mass fraction, λ, of the ambient air stream to divert intothe wet and dry passageways to achieve the desired temperature.
 23. Amethod as set forth in claim 22 further comprising adjusting a positionof the sheet valve to block the predetermined portion of the wet airoutlet and the dry air outlet to achieve λ and the desired temperature.24. A method as set forth in claim 22 wherein the step of determining λis based upon the following equation:$\lambda = \frac{c_{pa}\left( {T_{i} - T_{dpi}} \right)}{\left( {\omega_{\infty} - \omega_{i}} \right)h_{fg}}$wherein c_(pa) is the isobaric specific heat of air, Btu/lb_(m)° R, andh_(fg) is the latent heat of evaporation of the liquid.
 25. A method asset forth in claim 24 wherein h_(fg) is based upon the followingequation: $\begin{matrix}{h_{fg} = {\beta\left( {1 - \frac{T_{i}}{T_{c}}} \right)}^{3/8}} & \quad\end{matrix}$ wherein β is a constant=1300.26 Btu/lb_(m), and T_(c) isthe critical temperature of the liquid.
 26. A method as set forth inclaim 22 further comprising adjusting a flow rate of the ambient airinto the ambient air inlet to achieve the desired temperature.
 27. Amethod as set forth in claim 21 wherein the step of determining as isbased upon the following equation:$\omega_{i} = \frac{\left( {M_{w}/M_{a}} \right)\phi_{i}}{{\left( {P_{amb}/P_{wt}} \right)\exp\left\{ {\alpha\left\lbrack {\left( {T_{wt}/T_{i}} \right)^{4/3} - 1} \right\rbrack} \right\}} - \phi_{i}}$wherein T_(wt) is the triple point temperature of the liquid, P_(wt) isthe triple point pressure of the liquid, P_(amb) is the atmosphericpressure, M_(a) is the molecular weight of ambient air, M_(w) is themolecular weight of the liquid, and α is a dimensionlessconstant=15.0197.
 28. A method as set forth in claim 21 wherein the stepof determining ω_(∞) is based upon the following equation:$\omega_{\infty} = \frac{M_{w}/M_{a}}{{\left( {P_{amb}/P_{wt}} \right)\exp\left\{ {\alpha\left\lbrack {\left( {T_{wt}/T_{i}} \right)^{4/3} - 1} \right\rbrack} \right\}} - 1}$wherein T_(wt) is the triple point temperature of the liquid, P_(wt) isthe triple point pressure of the liquid, P_(amb) is the atmosphericpressure, M_(a) is the molecular weight of ambient air, M_(w) is themolecular weight of the liquid, and α is a dimensionlessconstant=15.0197.
 29. A method as set forth in claim 21 wherein the stepof determining T_(dpi) is based upon the following equation:$T_{dpi} - {T_{wt}\left\{ {1 - {\frac{1}{\alpha}1{n\left\lbrack \frac{\omega_{i}{P_{amb}/P_{wt}}}{\omega_{i} + {M_{w}/M_{a}}} \right\rbrack}}} \right\}^{{- 3}/4}}$wherein T_(wt) is the triple point temperature of the liquid, P_(wt) isthe triple point pressure of the liquid, P_(amb) is the atmosphericpressure, M_(a) is the molecular weight of ambient air, M_(wt) is themolecular weight of the liquid, and α is a dimensionlessconstant=15.0197.